Technical Field
The present disclosure relates to a covered wire including a covered conductor, a covered wire with terminal, a wire harness and a method of manufacturing a covered wire, and particularly relates to a covered wire, a covered wire with terminal, a wire harness and a method of manufacturing a covered wire in which detection of a defect such as a hole that is unintentionally produced in a covering layer in a manufacturing process is facilitated.
Background
In the related art, a so-called wire harness is used as an electric wiring structure for transportation vehicles such as automobiles, trains, and aircrafts, or an electric wiring structure for industrial robots. A wire harness is a member including covered wires each having a conductor made of copper or copper alloy, aluminum or aluminum alloy and fitted with terminals (connectors) made of copper or copper alloy (e.g., brass), aluminum or aluminum alloy. With recent rapid advancement in performances and functions of automobiles, various electrical devices and control devices installed in vehicles tend to increase in number, and electric wiring structures used for those devices also tend to increase in number. However, even if a defect such as a flaw, a crack, or a hole is produced in a covering layer unintentionally by some reason during the manufacturing process of a wire harness, an electric wire in which a defect has been produced could be directly assembled in a wire harness. In order to prevent such a situation, there is a need for a method with which a defect that is produced in a covering layer can be detected during a manufacturing process of a covered wire or a manufacturing process of a wire harness.
For example, by inspecting a covered wire immediately after a step of forming a covering layer over a conductor and detecting, by image analysis or the like, a defect formed in the covering layer, a covered wire in which a defect is produced can be removed as a reject product. However, if a defect is produced unintentionally in a subsequent step of manufacturing an electric wiring structure, which includes covered wires routed by bundling or the like, it is not possible to detect such a defect with the method mentioned above.
A covered wire of the related art used for an electric wiring structure of vehicles is described, for example, in Japanese Laid-Open Patent Publication No. 2004-134212, as an aluminum electric wire that is used for an automotive wire harness and having a characteristic equivalent to a copper wire.
However, the aforementioned Japanese Laid-Open Patent Publication No. 2004-134212 neither discloses nor suggests a method of defecting a defect that is produced in a covering layer.
Also, when manufacturing a covered wire, there is a method of detecting a defect in a covering layer with a flaw detector before a final winding-up step. However, with this method, it is not possible to detect a defect in the covering layer at the stage of manufacturing a wire harness using such covered wires.
The present disclosure is related to providing a covered wire, a covered wire with terminal, a wire harness and a method of manufacturing a covered wire, with which a defect that is produced in a covered wire manufacturing process as well as in a wire harness manufacturing process can be easily detected and further a defect in the wire harness can be easily detected.
For a covered wire that is applicable to a wire harness, the inventors have provided a plurality of inclusions between a conductor and a covering layer or in a covering layer, and carried out studies on an appropriate size and an appropriate density of the inclusions. As a result, the inventors have found that, in a case where a defect such as a flaw or a hole is produced in a covering layer in a process of manufacturing a covered wire or a wire harness, production of the defect can be easily detected utilizing the leakage of the inclusions from defect, and thus obtained the present invention.